Black Spots in Bathtub.

Some background info first.
I am in a brand new home, my water heater is a Bradford White 50 gallon.
It has a powervent installed. The 2" into 3" PVC vent pipe goes up about 2 feet and then horizontally for about 15 feet where it vents out of the basement wall.
I have a 72" by 48" fiberglass tub in white.

I have the unit set above the normal heat to a hotter setting, but not the highest available.

We are on City water not a well.

I have noticed little black specks on the bathtub recently. There is no shower in the tub. They were not there for the first three months of use. When rubbed they spread like ladies mascara would spread. It takes some rubbing and cleaning to get rid of them.
I thought at first maybe it was some kind of mold, but since it was only inside the tub, I decided to clean it with a 50/50 bleach water mix.
I let the tub sit for 3 days and nothing else appeared.
But once I filled the tub again with hot water, the little specks appeared again.
They are not in the sinks or toilets.
The toilets "do" show a very light pink colored ring at water level if not flushed for a couple of days, which cleans off very easily.

Does anyone have any idea what this is called, what causes this and how I can get rid of it.
All help would be appreciated.
If you need more info please ley me know.

I'm not a plumber, but you're right, this does sound like some sort of mold or other microorganism. It is strange that you don't get the spots on the sink, but maybe it's because you use the sink more than the tub so that whatever is growing in the tub just doesn't have time to get established in the sink before you rinse the bowl. Or maybe you are using mouthwash which kills off the critters in the sink?

In any event, I think the idea of draining the water heater does make sense. I don't know if this happens in home water systems, but I do know there are some bacteria that thrive in hot water -- called "thermophiles." I believe these are the things that make the hot water pools in Yellowstone turn different colors.

Be patient -- you'll get more opinions as the pros have time -- don't forget that this is a *free* resource!

Thanks Steve,
But I have found that the spots only appear with hot water use, not cold water.
Don't know if this will help the experst in diagnosing or not.
Jim

SteveW said:

I'm not a plumber, but you're right, this does sound like some sort of mold or other microorganism. It is strange that you don't get the spots on the sink, but maybe it's because you use the sink more than the tub so that whatever is growing in the tub just doesn't have time to get established in the sink before you rinse the bowl. Or maybe you are using mouthwash which kills off the critters in the sink?

In any event, I think the idea of draining the water heater does make sense. I don't know if this happens in home water systems, but I do know there are some bacteria that thrive in hot water -- called "thermophiles." I believe these are the things that make the hot water pools in Yellowstone turn different colors.

Be patient -- you'll get more opinions as the pros have time -- don't forget that this is a *free* resource!

Do you have a water softener? It appears to be the magnesium sulfide specks caused by a reaction of soft water with the water heater's anode rod. If so, then either remove the anode rod, or replace it with an aluminum one.

I too have the EXACT same problem!!!! It's almost as if I wrote the post! I did flush my water heater and it was full of those black specs...tons of them. I ended up puting in a new hot water heater ,the manufacturer replaced it because they thought it was the heater too. But, after about a week maybe less the black specks returned! To this day on the rare occasion when my wife uses the jacuzzi the specks return and can only be removed with the Mr. Clean Magic Eraser. On some occasions I see a speck or two in the shower and kitchen sink. But, what's very odd is that our other tub does not have the problem??? I ran a tub full of cold water in the poblem tub and saw nothing.

What is this!!!!???? It seems to be mystifing everyone I talk to. The thread starter is the only person I know who has described my problem...EXACTLY!

Someone who woks for a city water plant said it was algae that is growing in the tank, some say it's an o-ring. But, neither explanation totally solves this mystery. Why is it not in the other tub? How come it rarely shows up in the showers, but ALWAYS in this one tub?? I don't have stainless steel braided hoses with o-rings just PVC with copper ends. To my knowledge no one on my street has this problem. I've called 2 plumbers and either left a voice mail or talk to the receptionist, but no one has returned my calls....very frustrating!! I know the thread starter and we can't be the only ones with this problem.

it seems we have sufficient information to be able to use rigor in our method.

1a. the tub "is fiberglass". Is this an acrylic coated tub?
1b. are the sinks made of the same material?

2. spots only appear "after hot water use". Has anyone put cold water in the tub to see whether eliminating that possibility is necessary?

david

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The tub is fiberglass...acrylic coated. Sinks are not made of the same material. I'm not certain what it's made of, but it's nothing exotic. Sinks like it can be found daily in any Lowes, Home Depot of the like.

Let me claify something...what we have are small black particles that do not float which causes them to fall to the bottom. They almost stick to the surface and when you try to remove them they just smear like mascara or black grease. They are VERY hard to remove.

I ran a tub full of cold water and it was crystal clear. Run the tub full of hot or warm water and presto here come the black particles not several hundred maybe < than 25 per tub of water.

fast forward now to another approach: using a microscope, some of the specks that do come off easily, can be looked at closely. It's either organic growth (cells) or it's a substance.

If it does turn out to be something organic growing in the hot water pipes, the big question is, "what is organic food matter to it?". Secondly, what high temperature would kill it, in the HW heater, and would it still procreate in the pipes far enough away from the HW heater?

If it is a material, what is it?

Summary: Specks come from hot water only. Many were found in the previous HW heater when it was drained. There are occasional specks in all places, but not (not seen so far) in one of the two tubs. There are many in the one tub, an acrylic tub.

Please confirm this: you can see them flowing when the hot water is turned on and flowing; most of them fall and stick quite hard on the surface, whether it is acrylic or porcelain or another material.

fast forward now to another approach: using a microscope, some of the specks that do come off easily, can be looked at closely. It's either organic growth (cells) or it's a substance.

If it does turn out to be something organic growing in the hot water pipes, the big question is, "what is organic food matter to it?". Secondly, what high temperature would kill it, in the HW heater, and would it still procreate in the pipes far enough away from the HW heater?

If it is a material, what is it?

Summary: Specks come from hot water only. Many were found in the previous HW heater when it was drained. There are occasional specks in all places, but not (not seen so far) in one of the two tubs. There are many in the one tub, an acrylic tub.

Please confirm this: you can see them flowing when the hot water is turned on and flowing; most of them fall and stick quite hard on the surface, whether it is acrylic or porcelain or another material.

david

Click to expand...

Yes, you can see them flowing. I have a microscope(from my days as a kid in the late 70's) and had considered looking at them under it. On rare occasions I've seen them in my stainless steel kitchen sink.

Hi - sorry to be so late jumping in this thread, but I'm having the same problem with tiny black greasy spots. We've noticed the problem in my wife's bath - it seems to be hot water related - and we're noticing some spots on clothing from the washer. I had a plumber out and he said that we need to replace our hot water heater. It's only 8 years old. I drained a pan of water from it and it has the same black substance. I haven't noticed this in the showers, but maybe the shower head is filtering it, or maybe it's just washing down the drain before I see it.

Now for my question - I went to check water heaters and they are telling me that I also have to replace my existing expansion tank. Does that sound right?
Do those tanks go bad as well?

What about the anode rod - could it be a factor in the black spots? If so, should that be replaced with a different type whenever we get a new heater?

Turn the WH off, flush it out as well as you can until it runs clean. Fill it back up, turn it back on, set it to as hot as it will get and let it sit overnight. Then, turn it off again (you can shower, etc in the morning), flush it again. Then, see what happens.

I've read that sometimes if you are using a flexible connection on the supply to the WH, some have rubber internally, and it can degrade. Replacing them might solve the problem if that is the case.

Expansion tanks have a rubber bladder in them, and yes, it could be bad as well...they do eventually wear out. I suppose the black specs could also be coming from the breakdown of the rubber in it as well. If you knock on it, it should sound hollow (empty). If it is full of water, it's probably shot. It should be mostly filled with air. It has an air valve on the bottom (like a car tire). If you have the water supply to the house turned off and have opened a valve to relieve any pressure in the house, you can check the air pressure in the expansion tank. If you get water out of the valve, the tank is shot, replace it. If not, verify the pressure. It should be about the same as your normal water pressure. If you don't know that, pick up a guage from a big box store for about $10, and check it first. It will fit onto any hose connection - the washing machine, an outside faucet, the drain from the WH, etc., or anywhere if you buy an adapter to screw it on.

Note, the expansion tank should be on the cold inlet, not on the hot side of the tank. If it is on the hot side, it has other problems, and will die sooner, and give other problems.

Since you have an expansion tank, you probably either have a pressure reduction valve, or, less likely, a check valve to the house. The prv has rubber in it that could also be shot and spewing black specs into the water stream.